Hose clamps made from tubular stock with one or more plastically deformable, so-called "Oetiker" ears, as disclosed in my prior U.S. Patents 2,614,304 and 3,082,498 have been used with great success for more than three decades. In order to bridge the gap which remains underneath the "Oetiker" ear after contraction thereof, insert rings as disclosed in my prior U.S. Pat. No. 3,303,669 or insert members as disclosed in my prior U.S. Pat. No. 3,789,463 have been used. Such insert members were also used with open clamps mechanically interconnected at overlapping band end portions, as disclosed in FIG. 12 of my prior U.S. Pat. No. 4,315,348. Though these insert rings, respectively, insert members also proved quite successful, they entailed the disadvantage of increased costs in manufacture and assembly and additionally exhibited steps in the areas of overlap with the clamping band. These steps were of lesser significance with the relatively soft hose materials made from rubber or rubber-like materials as used heretofore. However, with the advent of plastic, relatively thin hose materials having a high degree of hardness, however, even slight steps with the use of relatively thin band material for the insert rings or insert members represent a possible source of leakage.
My prior U.S. Pat. No. 3,286,314 in which the open band ends were connected with each other by a special type of riveted connection, proposed to bridge the gap underneath the so-called "Oetiker" ear by a continuation of the inner band end, terminating ahead of a step in the outer band portion. However, a discontinuity still existed at the end of the inner band portion. The German Gebrauchsmuster (DE-GM) 75 41 277.0 suggested for an open clamp with a riveted or welded connection of the overlapping band ends, a tongue-like extension in the inner band portion commencing within the area of the welded connection and engaging into a pressed-out groove in the outer band portion beginning directly at the leg of the ear opposite the welded connection. In addition to other drawbacks, the clamp disclosed in this German Gebrauchsmuster entailed the significant disadvantage that the gap underneath the ear was bridged by an only narrow tongue-like extension that offered limited resistance to outward deflection into the gap underneath the ear in the presence of temperature and/or pressure fluctuations.
To provide a completely satisfactory internal clamping surface devoid of any gap, discontinuity or step over the entire circumference of the clamp, clamp structures are disclosed in my prior U.S. Pat. Nos. 4,299,012 and 4,315,348 in which the end of an overlapped inner band portion is provided with a tongue-like extension adapted to engage in a tongue-receiving means provided in the outer band portion and commencing at a step. The tongue-receiving means may thereby be in the shape of a central pressed-out channel beginning at a first step-like portion which brings the remaining lateral band portions to the radial height of the channel and terminating in a second step-like portion located in a direction away from the ear-like structure or other tightening means. In the alternative, the tongue-receiving means is constituted by an aperture commencing within the area of the step-like portion and extending a certain distance in the circumferential direction away from the ear-like structure or other tightening means. Clamp structures utilizing the inventions of the two last-mentioned patents have proved immensely commercially successful. However, in case of clamp structures made from tubular endless stock, they still require an insert member underneath the ear, though such insert member may be provided with tongue-like extensions engaging in tongue-receiving means as described in these two last-mentioned patents.
The British Patent 1,064,048 discloses a clamp, intended to provide a continuous circle for surrounding a flexible tube to avoid an interruption which could result in squeezing out and pinching the tube during tightening. To that end, this patent suggested in one embodiment the use of a double ring formation for the main loop consisting of two superimposed convolutions of similar diameter made as a helical winding from a single length of wire with the loops provided at diametrically opposite ends with tightening loops. In another embodiment of this patent, the double ring formation for the main loop is made from two separate and similar members each including a main loop superimposed one on the other and welded together in such a manner that the tightening loops are disposed opposite one another. Apart from cost considerations, the clamp of this patent also entails drawbacks from an installation point of view, not to mention the fact that the two loops made of wire-like material do not offer a substantially flat internal clamping surface. Moreover, another serious drawback of the clamp disclosed in this patent resides in the fact that the two tightening loops cannot be closed at the same time with one and the same tool.
The European Patent 0 296 918 discloses an open clamp in which the overlapping band portions are mechanically connected by a hook and anchoring arrangement unable to provide any elastic yielding to compensate for changes in temperature and pressure as assured by so-called "Oetiker" ears. To impart some elastic compensating capability to the clamp disclosed in this patent, the patent proposes the use of tensional spring elements which are located on opposite sides of a longitudinal cut in the center of the band and spaced from each other in the circumferential direction. The arrangement described in this European patent is to assure that the tightening continuity be maintained over the entire periphery of a soft tube regardless of the deformation of the undulations represented by the tensional spring elements, owing to their spaced circumferential spacing on the two sides of the longitudinal cut in the band. However, this patent does not deal with those problems peculiar to clamps provided with plastically deformable "Oetiker" ears in which the gap underneath the ear that itself assures an elastic compensation for temperature and/or pressure changes, must be bridged in such a manner as to avoid a gap, discontinuity or step, and at the same time offer such a resistance as to preclude the hose from being squeezed into the remaining gap. Such resistance can be assured only by the full band width bridging the gap underneath the ear.